Nowadays, the optical touch device is one of electric devices to achieve a touch function. FIG. 1 is a schematic view of a conventional optical touch device with three image detecting components. Referring to FIG. 1, the conventional optical touch device 100 includes four light reflecting bars 112a, 112b, 112c and 112d orderly arranged along four sides of a rectangle. The optical touch device 100 further includes light emitting components 122a, 122b and 122c configured for emitting light to the four light reflecting bars 112a, 112b, 112c and 112d. The light emitting component 122a is disposed between two neighboring ends of the light reflecting bar 112a and the light reflecting bar 112b, the light emitting component 122b is disposed between two neighboring ends of the light reflecting bar 112b and the light reflecting bar 112c, and the light emitting component 122c is disposed between two neighboring ends of the light reflecting bar 112a and the light reflecting bar 112d. The four light reflecting bars 112a, 112b, 112c and 112d are configured for reflecting the light emitted from the light emitting components 122a, 122b and 122c. The optical touch device 100 further includes image detecting components 132a, 132b and 132c. The image detecting component 132a is disposed between the two neighboring ends of the light reflecting bar 112a and the light reflecting bar 112b, and the light emitting component 122a is positioned on the image detecting component 132a. The image detecting component 132b is disposed between the two neighboring ends of the light reflecting bar 112b and the light reflecting bar 112c, and the light emitting component 122b is positioned on the image detecting component 132b. The image detecting component 132c is disposed between the two neighboring ends of the light reflecting bar 112a and the light reflecting bar 112d, and the light emitting component 122c is positioned on the image detecting component 132c. 
However, the conventional optical touch device 100 has a blind zone problem. For example, a field of view (FOV) of the image detecting component 132b covers the light reflecting bar 112a and the light reflecting bar 112d. However, a clearance exists between the light reflecting bar 112a and the light reflecting bar 112d to place the image detecting component 132c. Since the image detecting component 132c cannot reflect light, the image detecting component 132b cannot detect the touch point C in the detecting area 150. Thus, the area 150 is the blind zone. Similarly, the image detecting component 132c also has the blind zone problem.
To solve the above problem, a conventional method is described in detailed by using the image detecting components to detect in turn and using the light emitting components to provide compensating light. For example, when the image detecting component 132b is detecting, the light emitting components 122a, 122b provide illuminating light with normal brightness, and the light emitting component 122c provides the compensating light with low brightness to compensate the brightness. Accordingly, the brightness of the clearance between the light reflecting bar 112a and the light reflecting bar 112d is similar with that of the light reflecting bar 112a and the light reflecting bar 112d. Thus, the blind zone problem may be solved. Similarly, when the image detecting component 132c is detecting, the light emitting component 122b is used for providing the compensating light.
However, it needs a complicate driving circuit to make the light emitting components 122b, 122c provide the illuminating light with normal brightness or the compensating light with low brightness depending on the situation. Therefore, the cost of the optical touch device is increased.